Alkali metal bicarbonate is a commodity reagent which has found application in a broad variety of products such as laundry detergents, deodorizers, creams and lotions, dentifrices, antacids, buffers, fungicides, and the like.
The inclusion of particulate alkali metal bicarbonate in a cosmetic deodorant stick or roll-on formulation provides a product with improved deodorant properties. Dimensional instability of a cosmetic stick or roll-on product containing bicarbonate ingredient, and the esthetic appearance and the "feel" on the skin, are among the difficulties encountered in the preparation of a low residue cosmetic antiperspirant-deodorant product. The high density of a suspended particle-phase of bicarbonate ingredient relative to the low density of an organic matrix phase contributes to the instability and settling of the bicarbonate particle phase in a cosmetic stick or roll-on personal care product.
In addition, a bicarbonate ingredient often is incompatible with the active astringent salts and with other ingredients of conventional cosmetic stick products. A bicarbonate ingredient in direct contact with acidic ingredients is susceptible to decomposition into carbon dioxide and water.
An additional factor is the risk of a fragrance ingredient incompatibility with bicarbonate and astringent ingredients.
There is continuing interest in the development of reagents such as alkali metal bicarbonate and ammonium bicarbonate which have a uniform fine grain particle size, and exhibit a novel combination of properties when utilized as an ingredient in personal care, biologically active, household, and specialty type products. There is also interest in the development of a bicarbonate powder which is in a form that is stable when blended with an acidic ingredient in a formulation.
Accordingly, it is an object of this invention to provide an alkali metal bicarbonate or ammonium bicarbonate powder which has a fine grain particle size, and which is free-flowing and essentially free of agglomerated solids.
It is another object of this invention to provide an encapsulated powder composition that is a blend of particles which are composed of polymer-coated crystallites of bicarbonate salt and fragrance compounds, and which have a lower density than the inner core bicarbonate crystallites of the encapsulated particles.
It is another object of this invention to provide a cosmetic deodorant product which has a content of an encapsulated liquid fragrance ingredient with controlled release properties.
It is a further object of this invention to provide a cosmetic deodorant product which, when applied to underarm surfaces, signals deodorizing activity by the release of a fragrance aroma.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.